1. Technical Field
The present invention relates in general to vapor deposition and, in particular, to an improved system, method and apparatus for batch vapor deposition of adhesion promoter for manufacturing imprinted discrete track media and bit-patterned media, and/or a mono-molecular layer of lubricant on magnetic recording media.
2. Description of the Related Art
The first step in the nanoimprinting process of discrete track media (DTM) or bit patterned media (BPM) is to apply an adhesion promoter (AP) onto the substrates. Without AP the resist material applied in the subsequent step would be peeled off from the substrate during the later release step. AP is normally applied through conventional spin-coating techniques. Spin-coating can only coat one side of the substrate at a time, and much of the expensive AP material is spun off and wasted during this inefficient process. Moreover, the throughput of spin-coating is limited to one substrate at a time. A more efficient process needs to be developed for coating both sides of a disk substrate at the same time, while using a minimal amount of AP material to reduce waste.
In a related matter, the areal density of magnetic recording media continues to increase. As a result, the thickness of the lubricant used to coat the media after the media is fabricated must become thinner to avoid affecting the performance of the media. Although currently not possible, the lubricant thickness is expected to approach the absolute minimum thickness of a single molecule of the lubricant (i.e., on the order of 6 to 8 Å). In the future, manufacturing processes will need to be capable of applying much thinner layers of lubricant to sustain the areal density requirements. At such minimal thicknesses, however, it is difficult to achieve uniformity and reproducibility using conventional liquid dipping processes, as the thickness-versus-concentration slope becomes steeper. Another drawback of the dipping process is its slow bonding kinetics due to air exposure after sputtering. In addition, the dipping process requires the use of a solvent, which further increases cost.
One known solution to these problems is vapor lubricant deposition, such as those disclosed in U.S. Pat. No. 6,183,831 to Hughes, and U.S. Pat. No. 6,830,600 to McLeod. In those processes, both sides of a single disk are exposed to a diffused lubricant vapor in a line of sight inside a vacuum chamber. Unfortunately, those processes produce excessive lubricant thicknesses. Additional drawbacks of such approaches are very low throughput and poor uniformity of lubricant thickness compared to dipping. Thus, an improved solution is needed for applying ultra-thin lubricant films on magnetic recording media.